The copending application filed simultaneously herewith and entitled "Identification of Metabolic Characteristics of Microorganisms", is incorporated herein by reference.
The present invention relates to test apparatus for determining a metabolic characteristic of a microorganism suspended in a medium.
The above copending patent application describes how several test tubes or other containers can be inserted into a hollow holder. The holder can be filled with a temperature stabilizing liquid that is thermally regulated so that the test tubes placed in the holder all reach the same equilibrium temperature. This copending application describes a method for placing microorganisms suspended in a medium in one of the test tubes. A reagent which may inhibit or enhance microorganism growth is placed in another one of the test tubes within the holder. In addition, a central test tube is filled with a washing fluid. Two temperature probes can be inserted, one into the microorganism-containing medium, the other in the reagent. After thermal equilibrium is reached, a quantity of reagent is transferred to the medium containing the microorganism. After an interval of time, any change of temperature caused by an alteration in the metabolic rate of the microorganism is recorded. Since two probes are used, a differential temperature can be measured. This approach is highly immune to common thermal affects that may effect both tubes identically. The central tube containing a washing fluid can be used to initially balance the instrument and can be used between tests to clean the probe tips.
It is known to use certain equipment in electronic instrumentation. For example, a Wheatstone bridge, as well as a differential amplifier is well known in the instrumentation art. It is also known to build an incubator having hollow walls filled with water whose temperature is regulated.
Accordingly, there is a need for providing apparatus which can perform test of the foregoing type so that a rapid and accurate measurement can be made of metabolic characteristics.